Cleanup: Remove unneeded forward declarations in ppapi.

ppapi/shared_impl/video_decoder_impl.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_SHARED_IMPL_VIDEO_DECODER_IMPL_H_
 #define PPAPI_SHARED_IMPL_VIDEO_DECODER_IMPL_H_
 
 #include <map>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ppapi/c/dev/ppb_video_decoder_dev.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/thunk/ppb_video_decoder_api.h"
 
 namespace gpu {
 namespace gles2 {
 class GLES2Implementation;
 }  // namespace gles2
 }  // namespace gpu
 
 namespace ppapi {
-namespace thunk {
-class PPB_Context3D_API;
-}  // namespace thunk
-}  // namespace ppapi
-
-namespace ppapi {
 
 // Implements the logic to set and run callbacks for various video decoder
 // events. Both the proxy and the renderer implementation share this code.
 class PPAPI_SHARED_EXPORT VideoDecoderImpl
     : NON_EXPORTED_BASE(public thunk::PPB_VideoDecoder_API) {
  public:
   VideoDecoderImpl();
   virtual ~VideoDecoderImpl();
 
   // PPB_VideoDecoder_API implementation.
@@ skipping 34 matching lines @@
   // In the out-of-process case, Context3D's gles2_impl() exists in the plugin
   // process only, so gles2_impl_ is NULL in that case.
   gpu::gles2::GLES2Implementation* gles2_impl_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoDecoderImpl);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_VIDEO_DECODER_IMPL_H_